The gap between the tractor and trailer or between succeeding trailers of a semi-trailer truck causes aerodynamic drag and air turbulence which decreases the fuel efficiency and handling of the truck, especially at highway speeds. To enhance the aerodynamics of the truck, various accessories have been developed to direct air flow smoothly around downstream or following trailers. Such accessories include air fairings and various types of cab extenders to direct air flow over the roof and sides of the trailer.
Cab extenders along the side of a cab must be able to effectively direct airflow while accommodating the relative movement of the tractor and adjacent trailer or between two adjacent trailers during a turn. To allow this relative motion, some cab extenders include mechanical assemblies which enable wind deflectors to pivot about a mechanical joint during a turn. For example, such cab extenders may include relatively mechanically complex and expensive spring loaded panels that pivot as the truck turns and then spring back into a straight position.
Cab extenders incorporating a flexible plastic flap bolted or otherwise fastened by a multiplicity of fasteners to a metal extender element are known. With this construction, the plastic flap simply flexes in the event it impacts a trailer during a turn. Known cab extenders of this type are of multiple piece construction thereby adding to their expense; require multiple fasteners making them labor intensive to install and replace; and/or have flaps which wrinkle during use, thereby detracting from their appearance and causing them to wear out sooner.
Therefore, a need exists for an improved cab extender that individually or collectively addresses these and other drawbacks of existing designs.